Trans-Neptunian objects

Since Pluto's downgrading to a dwarf planet, many scientists now consider Pluto and its moons TNOs.

The regions of space beyond Neptune include the:

Kuiper Belt

Scattered disc objects

Oort Cloud

Kuiper Belt

The Kuiper Belt lies between 4.3 and 6.4 billion km from the Sun and contains millions of small icy bodies or TNOs, including Pluto. It is named after Gerard Kuiper, the astronomer who proposed its existence in 1951.

Kuiper Beltobjects tend to orbit the Solar System on roughly the same plane as planets and have almost circular orbits. Some of the largest TNOs in the Kuiper Belt include Quaoar (around 1,250 km in diameter) and the dwarf planet Eris, which is larger than Pluto.